Conventionally, a machine for suctioning and exhausting air from a storage tank for sand in a molding machine comprises both a valve for suctioning air and a valve for exhausting air from a storage tank for sand (see, for example, Japanese Patent Laid-open Publication No. 2002-210541). Further, as the invention disclosed in Japanese Patent Laid-open Publication No. S52-26316, a seal (the seal 7 in that publication) that expands when compressed air is supplied is provided at the rim of the tip of a nozzle for filling the sand of the storage tank so as to tightly attach the nozzle to a flask.